Jim makes a bunch of good points here.
Take a look at the datasheet for the #31 snap on cores. Look on page 2, where
it show the series equivalent loss impedance for a single pass through the
core as a function of frequency.
Impedance is a the square of the turns ratio. At least for a first order
approximation. Jim's detailed papers can help you greatly beyond that.
https://www.newark.com/pdfs/datasheets/Fairrite/0431176451.pdf
73,
Paul Cianciolo, W1VLF
ARRL EMC Engineer
ARRL - The national association for Amateur RadioT
225 Main Street, Newington, CT 06111-1400 USA
Telephone: (860) 594-0392
FAX: (860) 594-0259
Email: w1vlf@arrl.org
World Wide Web: www.arrl.org
-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org@contesting.com> On Behalf Of Jim
Brown
Sent: Friday, May 1, 2020 5:10 PM
To: rfi@contesting.com
Subject: Re: [RFI] looking for larger size ferrites
What frequency(ies) are you trying to suppress? In general, simply clamping a
ferrite over coax or hard line is effective only from about
100-500 MHz, depending on the ferrite mix. Fair-Rite #31 or #43 below about 250
MHz, #61 above that. Multiple turns on Fair-Rite #31 are required below that
frequency.
http://k9yc.com/2018Cookbook.pdf
http://k9yc.com/ChokesVHF.pdf
I've found Arrow Electronics to be a great vendor for the the quantities of
parts that I need IF they have them in stock, and they stock a lot of
Fair-Rite. Shipping is free for a $50 order placed online. Other vendors and a
tutorial discussion of how ferrite chokes work are in this link.
http://k9yc.com/RFI-Ham.pdf
73, Jim K9YC
On 5/1/2020 11:56 AM, David Huff wrote:
> I am looking for a source of larger size ferrites, preferably clamp on style
> big enough to go over LDF4-50 cable. (16 to 18mm Inside Diameter)
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